(中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 采用二次擠壓工藝制備MB26(Mg-6.3Zn-0.7Zr-0.9Y-0.3Nd)鎂合金棒材，研究不同擠壓比對MB26合金組織性能的影響，通過金相(OM)、X射線衍射(XRD)、掃描電鏡(SEM)、透射電鏡(TEM)等手段分析稀土元素在合金中的分布及其對微觀組織的影響。結(jié)果表明：合金在二次擠壓過程中發(fā)生動態(tài)再結(jié)晶，隨著擠壓比的增加，再結(jié)晶晶粒細(xì)化，當(dāng)擠壓比λ=25時，平均晶粒尺寸為1.9 μm，合金力學(xué)性能達(dá)到最優(yōu)；合金經(jīng)擠壓變形后出現(xiàn)大量W(Mg3Y2Zn3) 相和β′(MgZn)相，均呈彌散分布，釘扎晶界，阻礙了動態(tài)再結(jié)晶晶粒的長大。通過數(shù)據(jù)擬合得到該合金屈服強(qiáng)度與晶粒尺寸的Hall-Petch關(guān)系。
關(guān)鍵字: MB26鎂合金；力學(xué)性能；擠壓比；再結(jié)晶
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:MB26 magnesium alloy (Mg-6.3Zn-0.7Zr-0.9Y-0.3Nd) rod was prepared by double extrusion. The effects of extrusion ratio and rare earth elements (RE) on the microstructure and properties of MB26 alloy, as well as the distribution of RE in the alloy, were investigated by OM, XRD, SEM and TEM. The results show that, the dynamic recrystallization occurs during the double extrusion, the recrystallized grain size decreases with the increase of extrusion ratio. When extrusion ratio λ=25, the grain size is 1.9 μm with better mechanical properties. The large amount of dispersed Mg3Y2Zn3 (W) and MgZn (β′) phases appear after extrusion pinned the grain boundary and hindered the growth of recrystallized grain. By data fitting analysis, the Hall-Petch relationship of yield strength and grain size was calculated.
Key words: MB26 magnesium alloy; mechanical properties; extrusion ratio; recrystallization
